   :expand        if true makes the canvas take the entire window
   :engine        can be :webgl :canvas or :auto (default :auto)
   :layers        A list of keywords to refer to layers, from bottom to top
+  :origins       A mapping of layer names to their origin positions. Default
+                 position is center. Positions can be :center :top :bottom
+                 :left :right :top-left :top-right :bottom-left :bottom-right
 
   and either:
 

                      )
          resize-fn (fn [width height]
                      (.resize renderer width height)
                      (doall (map (partial center-container! canvas)
                                  (map second layer))))
          expand-fn (fn [] (resize-fn (.-innerWidth js/window)
                                      (.-innerHeight js/window)))


        ]
    {
     :stage stage
     :origins origins
     :layers layers
     :layer
     (into {}
